Maternal Undernutrition Significantly Impacts Ovarian Follicle Number and Increases Ovarian Oxidative Stress in Adult Rat Offspring

BACKGROUND: We have shown recently that maternal undernutrition (UN) advanced female pubertal onset in a manner that is dependent upon the timing of UN. The long-term consequence of this accelerated puberty on ovarian function is unknown. Recent findings suggest that oxidative stress may be one mechanism whereby early life events impact on later physiological functioning. Therefore, using an established rodent model of maternal UN at critical windows of development, we examined maternal UN-induced changes in offspring ovarian function and determined whether these changes were underpinned by ovarian oxidative stress. METHODOLOGY/PRINCIPAL FINDINGS: Our study is the first to show that maternal UN significantly reduced primordial and secondary follicle number in offspring in a manner that was dependent upon the timing of maternal UN. Specifically, a reduction in these early stage follicles was observed in offspring born to mothers undernourished throughout both pregnancy and lactation. Additionally, antral follicle number was reduced in offspring born to all mothers that were UN regardless of whether the period of UN was restricted to pregnancy or lactation or both. These reductions were associated with decreased mRNA levels of genes critical for follicle maturation and ovulation. Increased ovarian protein carbonyls were observed in offspring born to mothers UN during pregnancy and/or lactation and this was associated with peroxiredoxin 3 hyperoxidation and reduced mRNA levels; suggesting compromised antioxidant defence. This was not observed in offspring of mothers UN during lactation alone. CONCLUSIONS: We propose that maternal UN, particularly at a time-point that includes pregnancy, results in reduced offspring ovarian follicle numbers and mRNA levels of regulatory genes and may be mediated by increased ovarian oxidative stress coupled with a decreased ability to repair the resultant oxidative damage. Together these data are suggestive of maternal UN potentially contributing to premature ovarian ageing in offspring

Effect of Maternal Undernutrition on the Presence of Ovarian Hyperoxidised Prx 3.

<p>Maternal UN resulted in the increased presence of hyperoxidised ovarian Prx 3 in chow-fed UNP and UNPL, but not UNL, offspring. <b>A</b>) Representative non-reducing Western blot of Prx 3; Prx 3 is visualised as a 42 kDa band, hyperoxidised Prx 3 is visualised as a low molecular weight band (20 kDa); <b>B</b>) Data are presented as % hyperoxidised ovarian Prx 3 (as a ratio of band densities) and graphed as means ± S.E.M.; Two-Way ANOVA Main Effects: maternal diet p<0.001; postnatal diet  = 0.036; interaction p<0.001. Holm-Sidak <i>Post-hoc</i> analyses: * p<0.001 compared to chow-fed Controls. # p<0.001 compared to Cont-HF. + p<0.05, chow vs. HF.</p

Effect of Maternal Undernutrition on Offspring Ovarian Primordial Follicle Number.

<p>Maternal UN occurring throughout pregnancy and lactation (UNPL) resulted in a significant reduction in offspring primordial follicle number. Data are presented as follicle number per mm3 of ovarian tissue; median ± upper and lower quartiles. Open bars correspond to a postnatal chow diet; closed bars correspond to a postnatal HF diet. Two-Way ANOVA Main Effects: maternal diet p = 0.035; postnatal diet  = 0.610; interaction p = 0.072. Holm-Sidak <i>Post-hoc</i> analyses: * p<0.001 compared to chow-fed Controls.</p

Phenotypic Data.

<p>Data are presented as mean ± SEM. <i>Post-hoc</i> analyses:</p><p>*p<0.001 compared to Controls;</p>#<p>p<0.05 compared to Cont-HF.</p><p>Abbreviations: AG, anogenital; BW, body weight; NA, nose to anus; NT, nose to tail.</p

Experimental Design.

<p>Schematic representation of the experimental design. There are four levels of maternal nutrition and 2 levels of post-weaning diet resulting in a total of 8 experimental groups in a fully balanced 4×2 design.</p

Effect of Maternal Undernutrition on Offspring Ovarian Secondary Follicle Number.

<p>Maternal UN occurring throughout pregnancy and lactation (UNPL) resulted in a significant reduction in offspring secondary follicle number. Data are presented as follicle number per mm3 of ovarian tissue; median ± upper and lower quartiles. Open bars correspond to a postnatal chow diet; closed bars correspond to a postnatal HF diet. Two-Way ANOVA Main Effects: maternal diet p = 0.004; postnatal diet  = 0.074; interaction p = 0.394. Holm-Sidak <i>Post-hoc</i> analyses: * p<0.001 compared to chow-fed Controls.</p